I don't know. I thought we were talking about micro-spheres/micro balloons. West Systems 406 doesn't contain any micro-spheres but rather colloidal silica. Colloidal Silica would be much stronger than micro-spheres.

I used colloidal silica, same as when joining wings. Very tough surface, and will continue using them for mold making!

I have fished up the first side of the wing mold. The actual layup ended up being a little different from what I stated at the beginning. I had a bunch of 6 oz. in stock so used that for the bulk of the layup.

The flange is reinforced with 1/2" end grain balsa core material. This is a boat builders core material. It was cheap a long time ago when bought a ton of it and have been using it for the last 15 years.
This makes a really stable flange with good clamping pressure. Im sure you could use metal like aluminum square tubing which would work good as well and be faster. But as I said, I have a lot of it.
The core material needs to be capped with glass to create a spar of sorts. It does not need to be as thick of a layup as the mold but reasonably close.

Before pulling the mold off the parting table I sanded the tips level and added a block on each end of some scrap Corian. Then made a center stand out of MDF left over from the parting trays.

The layup came off the table with out much effort and looked very nice. Just some minor cleanup and cut off the excess glass on the flange.
Now its time to repeat the process again.

Once the mold is done I will post more photos of the finished product. It may be a week or two before I finish up. Im starting a new shaping job hopefully next week back on the North Shore. Im looking forward to it. I've been out of the room for 4 years!

You never know, I may be doing some custom boards again. For now Im helping a friend shaping his boards off the CNC. Only a couple of days a week
so no big deal.
Really a nice drive from my house in Ewa to Wailua. Through the pineapple fields down to the North Shore, Dillingham Glider port 10 min. away. I just got a call from an old friend I used to build boards with and fly full scale out there. He's an Instructor out there now. Looks like I may have to go get checked out again. Fun, Fun, Fun.

Looks like I lost you guys using the end grain balsa. What this allows is a relatively light mold. There are a few reasons to go this way. If your 100 lb. sand backed mold takes a twist your screwed. The flexible mold can be set true by just tacking the corner down. Also removing parts is a dream because you can twist the entire mold enough to get parts out. They just pop out!
It is more work than just poring sand and resin on the back but it really pays off in ease of moving and storing.
I have fuse molds done this way that are 15 years old and the seams are still tight and and aligned. Only my molds that do not have the end grain on the flange have wandered, such as my DLG Pod molds and a couple of early TD
molds.

............................
Looks like I lost you guys using the end grain balsa. What this allows is a relatively light mold. There are a few reasons to go this way. If your 100 lb. sand backed mold takes a twist your screwed. The flexible mold can be set true by just tacking the corner down. Also removing parts is a dream because you can twist the entire mold enough to get parts out. They just pop out!
It is more work than just poring sand and resin on the back but it really pays off in ease of moving and storing.
I have fuse molds done this way that are 15 years old and the seams are still tight and and aligned. Only my molds that do not have the end grain on the flange have wandered, such as my DLG Pod molds and a couple of early TD
molds.

Dave

Yes Dave, you had lost me for a while there. However, the above description is very persuasive! I really like the "twist the entire mould" and "they just pop out" part!
Got me thinking and re-thinking!

You never know, I may be doing some custom boards again. For now Im helping a friend shaping his boards off the CNC. Only a couple of days a week
so no big deal.
Really a nice drive from my house in Ewa to Wailua. Through the pineapple fields down to the North Shore, Dillingham Glider port 10 min. away. I just got a call from an old friend I used to build boards with and fly full scale out there. He's an Instructor out there now. Looks like I may have to go get checked out again. Fun, Fun, Fun.

Dave

Life is tough! man, just reading that has me back there...

Good luck back in the shaping bay, maybe a picture of one of those too?

Twist capability

Dave,

Your end grain balsa has given me some inspiration to try another construction method I have seen here somewhere. My latest plan (I have had a few changes of mind), is to make the mould skin around 5 mm or so like you do and use a 30mm RHS steel frame to support the flange. This would keep the LE and TE nice and straight while allowing a small amount of twist (possibly 1 or 2 mm?) for the initial breaking of the plug out of the mould.

How does the Duratec compare to conventional spray on Gel coat in terms of sanding ease? I am thinking this due to one reason only. I can obtain very small quantities of this locally while with the Duratec I have to buy the full 1 gallon as that is all Aus suppliers sell. Or at least, that is all that I have been able to find yet.
It is clear that the Duratec will be superior as it has been designed specifically for plug preparation. But I'm just thinking of a more economic alternative for small hobby scale jobs like mine etc.

Gel coat will work but takes much longer to cure. You will have to add a surfacing agent to it so you can sand it. It will polish out nicely though.
When you spray it, it will tend to go on with a lot of orange peel texture requiring more sanding than Duratec.

Gel coat will work but takes much longer to cure. You will have to add a surfacing agent to it so you can sand it. It will polish out nicely though.
When you spray it, it will tend to go on with a lot of orange peel texture requiring more sanding than Duratec.

Dave

Yes Dave. I have had a plug or two sprayed for me in gel coat by local friendly fibreglass workers so I know about the orange peel texture.
I have some months to find others to share of a gallon of Duratec, so I will be working towards using that I think.

Progress report : The mold has been completed or lets say the glass layups are done.
Its resting quietly now, curing for a week before I trim the edges and open that sucker up! Easy to say but man thats hard to do, you just want to start playing with it.